Lionel Messi ruined the contest unforgettably. Arsène Wenger was reduced to awe more than misery, particularly by the fourth and last of his goals. "He made the impossible possible," said the Arsenal manager. "He has six or seven years in front of him, touch wood that nothing happens to him, and he can reach unbelievable levels."

Without Messi this would have been a close and absorbing match, ludicrous though it sounds. He pulled off quite a trick in making the remainder of an outstanding team look lesser beings but even the best of them must know the luck they enjoy in being part of his retinue. That is a far better role to occupy than that of a defender who is supposed to exercise some control over Messi.

The blaze of his play burnt away nearly everything else in this occasion. Concentration is called for just to summon up the memory that Nicklas Bendtner had scored an opener that put Arsenal ahead on aggregate following the 2-2 draw at the Emirates. Messi, by his unfeasibly grand standards, had been off form that night but the balance was redressed thrillingly in this match.

It could be that Arsenal will take comfort from the knowledge that almost anyone would be found wanting when put to such a test. They are not quite out of the battle for the Premier League but they do lag and the likelihood is that this will be another season in the trophyless run that began after the 2005 FA Cup final had been seized.

Wenger, all the same, is not peddling propaganda when he holds forth on the potential of players whose best years should lie ahead. It was unhelpful, too, that a defender such as William Gallas had experienced what looks like an early close to the campaign. As in the first match the manager resisted any temptation to name the veteran Sol Campbell in the line-up.

This can be explained politely by reference to a calf injury sustained against Wolverhampton Wanderers last weekend but the centre-half was in good enough shape to be among the substitutes. That was the safest place for an Arsenal defender. Thomas Vermaelen and Mikaël Silvestre had a horrible time of it. The introduction of Emmanuel Eboué for the latter could easily have been mistaken for a humanitarian gesture by Wenger.

Their distress had been beyond imagination when Arsenal had an initial confidence that led to the opener. The manager has had cause to detect a rising competitiveness about his squad and that was reflected in the opener in the 19th minute. Abou Diaby put in a challenge on Gabriel Milito that the referee Wolfgang Stark deemed legitimate and Theo Walcott was then released on the right.

The winger ran towards the middle before setting up Bendtner. The first attempt was saved by Victor Valdes but the Dane composed himself to clip in the rebound. Walcott's speed had devastated Barcelona, as Wenger intended, but nothing that ensued owed much to tactics or other pre-planned manoeuvres.

Barcelona's response three minutes later had its roots in a haphazard event that flowered into majesty. Silvestre half-cleared but got the ball no further than Messi, who settled himself before shooting unanswerably into the top corner from the edge of the penalty area. After that there was not so much a match to be recorded as a record to be maintained of virtuosity.

Eight minutes from half-time the left-back Eric Abidal overlapped and, when his cross was half-cleared, Pedro was able to recover and lay the ball back to Messi. The forward, awash with infallibility, clipped the finish home as Manuel Almunia was advancing in the misplaced hope of smothering any effort. After 42 minutes a Seydou Keita header put Messi through to lift the ball over Almunia.

Arsenal cannot have identified much solace in these events, although they may ultimately come to the conclusion that anyone would have been in torment and it was simply their bad luck to be around when Messi was exceptional even by his own uncanny expectations.

There was a mistaken feeling in the second half that he had located clemency in his heart while he pretended to be a normal footballer. The truth was revealed yet again in the 88th minute. Messi broke from the centre towards the left and when Almunia blocked the first effort the next went through the goalkeeper's legs. It is clearly excessive that the scorer should also have luck in his armoury.

Messi's irrepressibility will now be a feature in a semi-final of contrasts. Barcelona take on Internazionale and their manager, José Mourinho, prides himself on shaping events from the sidelines. It is hard to think of anyone less likely than Messi to be nullified by mere strategy but there is no question that the Portuguese will think it feasible.

Arsenal must turn away to less exalted issues. Even here there was for a while a demonstration of the conviction that runs through an emerging side. It was proof of their character that they so evidently believed at the outset that they could prevail at Camp Nou. That outlook will serve them well at lesser arenas in the years ahead.